Lens unit, imaging device, and control method

ABSTRACT

There is provided a lens unit equipped with multiple focus lenses provided inside a lens barrel, multiple actuators corresponding to the respective multiple focus lenses and configured to move each of the multiple focus lenses inside the lens barrel, and a control circuit configured to control movement of the multiple focus lenses according to different rules between a case of a position of each of the multiple focus lenses being inside a designated range of satisfactory optical performance, and a case of being outside the range.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Japanese Priority PatentApplication JP 2016-017925 filed Feb. 2, 2016, the entire contents ofwhich are incorporated herein by reference.

BACKGROUND

The present disclosure relates to a lens unit, an imaging device, and acontrol method.

Technologies related to a lens unit equipped with multiple lenses forrealizing a function of adjusting focus are being developed. Onetechnology related to a lens unit equipped with multiple lenses isdescribed in JP 2014-44223A, for example.

SUMMARY

Contrast autofocus (hereinafter also designated “contrast AF”) is onemethod of adjusting focus automatically. When contrast autofocus isused, the in-focus point is detected on the basis of an approximatecurve obtained from acquired contrast values, and thus contrast valueson either side of the in-focus point need to be acquired. Also, eachcontrast value is acquired by moving each of multiple focus lensesconstituting a lens unit.

However, because of factors such as physical limitations on focus lensmovement due to the configuration of the lens unit, for example, asituation may occur in which a focus lens is not sufficiently moved overa desirable range for acquiring contrast values for conducting contrastAF. As above, if a focus lens is not sufficiently moved over a desirablerange for acquiring contrast values, or in other words, if aninsufficiency of movement is produced in a focus lens, there is a riskof being unable to conduct contrast AF with sufficient accuracy.

The present disclosure proposes a new and improved lens unit, imagingdevice, and control method enabling a resolution of an insufficiency offocus lens movement which may be produced when conducting contrastautofocus.

According to an embodiment of the present disclosure, there is provideda lens unit equipped with multiple focus lenses provided inside a lensbarrel, multiple actuators corresponding to the respective multiplefocus lenses and configured to move each of the multiple focus lensesinside the lens barrel, and a control circuit configured to controlmovement of the multiple focus lenses according to different rulesbetween a case of a position of each of the multiple focus lenses beinginside a designated range of satisfactory optical performance, and acase of being outside the range.

Additionally, according to an embodiment of the present disclosure,there is provided an imaging device equipped with a lens unit and animaging unit. The lens unit includes multiple focus lenses providedinside a lens barrel, multiple actuators corresponding to the respectivemultiple focus lenses and configured to move each of the multiple focuslenses inside the lens barrel, and a control circuit configured tocontrol movement of the multiple focus lenses according to differentrules between a case of a position of each of the multiple focus lensesbeing inside a designated range of satisfactory optical performance, anda case of being outside the range.

Additionally, according to an embodiment of the present disclosure,there is provided a control method executed by a control circuit of alens unit. The control method includes controlling movement of multiplefocus lenses provided inside a lens barrel according to different rulesbetween a case of a position of each of the multiple focus lenses beinginside a designated range of satisfactory optical performance, and acase of being outside the range.

According to an embodiment of the present disclosure, it is possible toresolve an insufficiency of focus lens movement which may be producedwhen conducting contrast autofocus.

Note that the effects described above are not necessarily limited, andalong with or instead of the effects, any effect that is desired to beintroduced in the present specification or other effects that can beexpected from the present specification may be exhibited.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory diagram illustrating an example of aconfiguration of a lens unit according to an embodiment;

FIG. 2 is an explanatory diagram for illustrating a control methodaccording to an embodiment;

FIG. 3 is an explanatory diagram for illustrating a control methodaccording to an embodiment;

FIG. 4 is an explanatory diagram for illustrating a control methodaccording to an embodiment;

FIG. 5 is an explanatory diagram for illustrating a control methodaccording to an embodiment;

FIG. 6 is a block diagram illustrating an example of a configuration ofa lens unit according to an embodiment;

FIG. 7 is a flowchart illustrating an example of a process conducted bythe imaging device illustrated in FIG. 6;

FIG. 8 is a flowchart illustrating an example of a process conducted bya lens unit according to an embodiment; and

FIG. 9 is a block diagram illustrating an exemplary configuration of animaging device according to an embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENT(S)

Hereinafter, (a) preferred embodiment(s) of the present disclosure willbe described in detail with reference to the appended drawings. In thisspecification and the appended drawings, structural elements that havesubstantially the same function and structure are denoted with the samereference numerals, and repeated explanation of these structuralelements is omitted.

The description hereinafter will proceed in the following order.

-   -   1. Control method according to embodiment    -   2. Lens unit and imaging device according to embodiment    -   3. Program according to embodiment

Control Method According to Embodiment

First, a control method according to an embodiment will be described.Hereinafter, an example will be given in which a lens unit according tothe present embodiment conducts a process in accordance with a controlmethod according to the present embodiment.

In addition, the following primarily describes an example for a singlefocus point, or in other words, a case in which the focal length isfixed, and the object distance (typically the distance between theimaging device and the in-focus image plane; also called the “subjectdistance”) moves with respect to this focal length. However, the controlmethod according to the present embodiment is not limited to beingapplied to a single focus point. For example, the control methodaccording to the present embodiment may also be applied to the case of avariable focal length.

FIG. 1 is an explanatory diagram illustrating an example of aconfiguration of a lens unit according to the present embodiment. FIG. 1is a simplified illustration of the lenses provided in a lens barrel(not illustrated) and various mechanisms such as an actuator and a camring. The lenses provided in the lens barrel (not illustrated) includevarious lenses, such as a focus lens, a zoom lens, and a fixed focallength lens, for example.

Note that in the lens unit according to the present embodiment, thefocus lens may be the same lens as other lenses, such as the zoom lens.For example, the case of the focus lens and the fixed focal length lensbeing the same lens corresponds to an example of the case of a singlefocus point. As another example, the case of the focus lens and the zoomlens being the same lens corresponds to an example of the case of avariable focal length. As discussed above, the following describes acontrol method according to the present embodiment while presupposing asingle focus point. Also, in the case of a variable focal length, the“range of satisfactory optical performance” discussed later changes formultiple focus lenses.

The sign L1 illustrated in FIG. 1 represents one focus lens, while thesign M1 illustrated in FIG. 1 represents an actuator that moves thefocus lens L1 inside the lens barrel. Also, the sign L2 in FIG. 1represents another focus lens, while the sign M2 illustrated in FIG. 1represents a cam ring. Also, although not illustrated in FIG. 1, thelens unit according to the present embodiment is equipped with anactuator that moves the focus lens L2 inside the lens barrel.

The focus lens L1 and the focus lens L2 are made up of one focus lenseach. Also, one or both of the focus lens L1 and the focus lens L2 maybe a lens group made up of multiple sub-lenses. In addition, the focuslens L1 and the focus lens L2 may move inside the lens barrel accordingto the corresponding actuator of each. To take FIG. 1 as an example,each of the focus lens L1 and the focus lens L2 may move inside the lensbarrel in the left and right direction of FIG. 1 along the optical axis.

Note that the number of focus lenses provided in the lens unit accordingto the present embodiment is not limited to two like the focus lens L1and the focus lens L2 illustrated in FIG. 1. For example, the lens unitaccording to the present embodiment may also be provided with three ormore focus lenses. The lens unit according to the present embodiment maytake a configuration in which at least one of the multiple focus lensesis a lens group made up of multiple sub-lenses. Hereinafter, for thesake of convenience, an example will be described in which the lens unitaccording to the present embodiment is provided with two focus lensesdesignated the focus lens L1 and the focus lens L2.

As discussed above, when contrast AF is conducted, for example, aninsufficiency of movement may be produced in a focus lens due to factorssuch as physical limitations on focus lens movement due to theconfiguration of the lens unit. Hereinafter, this insufficiency ofmovement in a focus lens may also be referred to simply as an“insufficiency”.

FIG. 2 is an explanatory diagram for illustrating a control methodaccording to the present embodiment, and illustrates an example of aninsufficiency of focus lens movement that may be produced when contrastAF is conducted. FIG. 2 illustrates a relationship between positions ofa certain focus lens and contrast AF detection values (this correspondsto the contrast values discussed earlier).

As illustrated in FIG. 2, for a certain focus lens, there exists a“physically focusable range of motion” labeled A in FIG. 2, caused byfactors such as physical limitations due to the configuration.

In addition, for a certain focus lens, a “range of satisfactory opticalperformance” labeled B in FIG. 2 is set inside the “physically focusablerange of motion”. Herein, “satisfactory optical performance” accordingto the present embodiment refers to satisfying a preset modulationtransfer function (MTF) with respect to another focus lens thatcooperates with the relevant focus lens, for example. The infinity sideof the “range of satisfactory optical performance” is called “INF”,while the minimum object distance side of the “range of satisfactoryoptical performance” is called “MOD” (minimum object (optical)distance). Hereinafter, the object distance corresponding to “INF” isdesignated the “object distance 1”, and the object distancecorresponding to “MOD” is designated the “object distance 2”.

If the position of the focus lens exists inside the “range ofsatisfactory optical performance” labeled B in FIG. 2, this means thatthe relevant focus lens and other cooperating focus lenses may beutilized to capture an image with satisfactory optical performance. Ifthe object distance based on multiple focus lenses is included betweenthe object distance 1 and the object distance 2, a preset MTF will besatisfied in each image plane from the object distance 1 to the objectdistance 2. Also, if the preset MTF is satisfied, the focus lens groupconstituting the multiple focus lenses exists inside the “range ofsatisfactory optical performance” labeled B in FIG. 2.

In addition, when contrast AF is conducted, there exists a desirablerange for acquiring contrast values for conducting contrast AF, like the“desirable range of motion for contrast AF” labeled C in FIG. 2.

For example, as illustrated in FIG. 2, when the peak position of theapproximate curve obtained from the contrast values, or in other words,the in-focus point for contrast AF, exists near the object distance 1, asituation may occur in which the “desirable range of motion for contrastAF” labeled C in FIG. 2 is not included in the “physically focusablerange of motion” labeled A in FIG. 2. One example of a case in which thein-focus point exists near the object distance 1 is the case in whichcontrast AF is conducted on a subject present near the object distance1, for example.

Furthermore, the range of the “desirable range of motion for contrastAF” labeled C in FIG. 2 that is not included in the “physicallyfocusable range of motion” labeled A in FIG. 2 corresponds to the“insufficiency” labeled D in FIG. 2.

When contrast AF is conducted, if an “insufficiency” like the onelabeled D in FIG. 2 is produced, contrast values are not obtainedadequately, and there is a risk of being unable to conduct contrast AFwith adequate accuracy.

Accordingly, the lens unit according to the present embodiment conductsa “process of controlling the movement of multiple focus lenses”(hereinafter designated the “movement control process”) as a processaccording to a control method according to the present embodiment.

In the lens unit according to the present embodiment, the movementcontrol process according to the present embodiment is conducted by acontrol circuit provided in the lens unit according to the presentembodiment, for example.

The control circuit controls the movement of multiple focus lenses bycontrolling the operation of the multiple actuators corresponding to therespective multiple focus lenses. The control circuit controls theoperation of the actuators by transmitting, to an actuator to becontrolled, a control signal that controls the operation of theactuator, for example.

Herein, each actuator according to the present embodiment causes acorresponding focus lens to move inside the lens barrel, as describedwith reference to FIG. 1. Thus, by controlling the operation of anactuator, the control circuit is able to cause the focus lenscorresponding to that actuator to move inside the lens barrel accordingto the control of the operation of the actuator. An example of thecontrol circuit that conducts the movement control process will bediscussed later.

More specifically, the lens unit according to the present embodimentcontrols the movement of the multiple focus lenses by changing the rulesregarding the movement of the multiple focus lenses between a “case inwhich the position of each of the multiple focus lenses is inside adesignated range of satisfactory optical performance”, and a “case inwhich the position of each of the multiple focus lenses is outside thedesignated range of satisfactory optical performance”. In other words,the lens unit according to the present embodiment controls the movementof the multiple focus lenses according to different rules depending onwhether the position of each of the multiple lenses is in-range orout-of-range.

Herein, “in-range” according to the present embodiment refers to therange of positions of the focus lenses that enables imaging withsatisfactory optical performance using the focus lenses. Also,“out-of-range” according to the present embodiment refers to the rangeof positions of the focus lenses that does not enable imaging withsatisfactory optical performance using the focus lenses. When theposition of each of the multiple focus lenses is in-range, the objectdistance based on the multiple focus lenses becomes positioned betweenthe minimum object distance (the object distance 1 illustrated in FIG.2) and infinity (the object distance 2 illustrated in FIG. 2), like the“range of satisfactory optical performance” labeled B in FIG. 2. Forexample, in some cases the optical performance may be unsatisfactory dueto physical limitations on the focus lens inter-group distance(discussed later).

In other words, one example of a case in which the positions of thefocus lenses are in-range is the case in which the positions of thefocus lenses are inside the “range of satisfactory optical performance”labeled B in FIG. 2. Also, one example of a case in which the positionsof the focus lenses are out-of-range is the case in which the positionsof the focus lenses are inside the “physically focusable range ofmotion” labeled A in FIG. 2, but not inside the “range of satisfactoryoptical performance” labeled B in FIG. 2. As discussed above, the “rangeof satisfactory optical performance” is obtained based on whether or nota preset MTF is satisfied, for example.

Rules regarding the movement of the multiple focus lenses according tothe present embodiment are prescribed by a movement profile, forexample.

Herein, a movement profile according to the present embodiment issettings information related to control of the movement of the focuslenses. Examples of movement profiles according to the presentembodiment include, for example, data indicating a relational expressionof satisfactory optical performance expressing a relationship betweenthe amount of blur and the amount of movement, or a table (or adatabase; this applies similarly hereinafter) associating the amount ofblur with the amount of movement of each focus lens obtained from theabove relational expression of satisfactory optical performance.

In a case that the lens unit is a zoom lens unit which has the zoomlens, the lens unit can have a plurality of the movement profilescorresponding to each of focal lengths.

The lens unit according to the present embodiment controls the movementof the multiple focus lenses when in-range and the movement of themultiple focus lenses when out-of-range on the basis of differentmovement profiles, for example. In other words, the lens unit accordingto the present embodiment switches the movement profile to use forcontrol between the case in which the position of each of the multiplefocus lenses is in-range, and the case in which the position of each ofthe multiple focus lenses is out-of-range, for example. Herein,switching the movement profile to use for control corresponds toswitching the rules regarding the movement of the multiple focus lenses.

By controlling the movement of the multiple focus lens on the basis ofdifferent movement profiles between the case in which the position ofeach of the multiple focus lenses is in-range and the case in which theposition of each of the multiple focus lenses is out-of-range, the rulesregarding the movement of the multiple focus lenses change between thecase of being in-range and the case of being out-of-range.

In addition, the lens unit according to the present embodiment conductsthe movement control process on the basis of control information. Thecontrol information that the lens unit according to the presentembodiment uses in the movement control process is acquired from animaging unit according to the present embodiment, for example.

The control information according to the present embodiment is dataindicating the amount of blur per unit time, for example. The controlinformation is generated by the imaging unit according to the presentembodiment, for example. In the imaging unit according to the presentembodiment, the amount of blur per unit time is determined on the basisof the detection result of a signal obtained by imaging through the lensunit according to the present embodiment.

Herein, the unit time according to the present embodiment may be a fixedamount of time, such as 1 [sec] or 2 [sec], for example, or a variableamount of time that may be set based on a user operation or the like.Hereinafter, a case in which the unit time according to the presentembodiment is 1 [sec] will be described as an example.

Also, the amount of blur according to the present embodiment is a valueindicating the degree of defocusing after the unit time at an arbitraryposition of interest in-range, for example. The amount of blur accordingto the present embodiment may also be called the “amount of defocus”,for example.

In addition, “defocusing” according to the present embodiment refers to“changing the spatial frequency (lowering the spatial frequency)” or“changing the deviation from the imaging plane (increasing thedeviation)” by changing the focal depth (image plane).

Note that the control information according to the present embodiment isnot limited to the above data indicating the amount of blur per unittime. For example, the control information according to the presentembodiment may also be one or both of data indicating the amount ofmovement of the multiple focus lenses, and data indicating the movementspeed of the multiple focus lenses. In addition, the control informationaccording to the present embodiment may also be data indicating theposition of a focus lens, for example. At this point, examples of dataindicating position in the case in which the lens unit according to thepresent embodiment includes multiple focus lenses include, for example,data indicating the position of each of the multiple focus lenses, ordata indicating a virtual position when treating the multiple focuslenses as a single focus lens. Hereinafter, a case in which the controlinformation according to the present embodiment is data indicating theamount of blur per unit time will be described as an example.

The imaging unit according to the present embodiment determines theamount of blur per unit time based on data indicating the contrastobtained from a signal obtained by components such as an image sensor, afilter, and a detection circuit, for example (for example, dataindicating contrast AF detection values; this is one example of adetection result of a signal obtained by imaging).

Herein, the lens unit according to the present embodiment and theimaging unit according to the present embodiment may be unitsconstituting a single device, or separate units. If the imaging unitaccording to the present embodiment and the lens unit according to thepresent embodiment are separate units, the imaging unit according to thepresent embodiment functions as an imaging device (also referred to asthe camera body), while the lens unit according to the presentembodiment functions as an interchangeable lens. An example of theconfiguration in the case of the lens unit according to the presentembodiment and the imaging unit according to the present embodimentbeing units constituting a single device, and an example of theconfiguration in the case of the lens units according to the presentembodiment and the imaging unit according to the present embodimentbeing separate units, will be discussed later.

Note that if the control information is acquired from an external devicesuch as the imaging unit according to the present embodiment, theexternal device transmits control information specifying the amount ofblur per unit time, for example. However, the lens unit according to thepresent embodiment may not be dependent on an external device totransmit control information in some cases, depending on how the amountof blur per unit time is realized. In other words, the lens unitaccording to the present embodiment may also conduct the movementcontrol process on the basis of acquired control information, withoutdepending on an external device to transmit control information. Oneexample of a movement control process based on acquired controlinformation in the lens unit according to the present embodiment is, forexample, a process of controlling the movement of multiple focus lenseson the basis of control information, with different rules regarding themovement of the multiple focus lenses for the in-range case andout-of-range case, so that the movement of the multiple focus lenses inthe in-range case and the out-of-range case is considered equal withrespect to the amount of blur per unit time indicated by the controlinformation.

Thus, even assuming that an external device that transmits controlinformation, such as the imaging unit according to the presentembodiment, evolves to become more multi-functional and advanced, thelens unit according to the present embodiment is able to conduct themovement control process without depending on such an external device.Consequently, when the lens unit according to the present embodiment isused, even assuming that an external device that transmits controlinformation, such as the imaging unit according to the presentembodiment, evolves to become more multi-functional and advanced,compatibility with such an external device may be ensured.

The lens unit according to the present embodiment controls the movementof the multiple focus lenses so that the amount of blur indicated by thecontrol information is satisfied in the case in which the position ofeach focus lens is in-range, and the case in which the position of eachfocus lens is out-of-range.

The lens unit according to the present embodiment determines the amountof movement by which to move each focus lens on the basis of the amountof blur indicated by the control information. Subsequently, the lensunit according to the present embodiment controls the movement of themultiple focus lenses by moving the multiple focus lenses by thedetermined amount of movement.

Herein, the lens unit according to the present embodiment determines amovement speed per unit time for each of the multiple focus lenses, onthe basis of the amount of blur indicated by the control information,for example. By determining a movement speed per unit time, an amount ofmovement per unit time by which to move each focus lens may be obtained.Note that the lens unit according to the present embodiment may alsodetermine the amount of movement per unit time without determining themovement speed per unit time.

As discussed above, in the lens unit according to the presentembodiment, the movement control process is conducted by the controlcircuit. In addition, the control circuit moves a focus lens bytransmitting a control signal to an actuator to be controlled andcontrolling the operation of that actuator. The control circuit controlsthe movement of each of the multiple focus lenses by transmitting toeach actuator a control signal including a command causing a focus lensto be moved by a determined amount of movement. In other words, theamount of movement determined in the control circuit corresponds to adriving amount by which to cause an actuator to operate.

In the lens unit according to the present embodiment, the controlcircuit controls the operation of the actuators on the basis of thecontrol information as above, and thus the amount of blur is controlled.

The lens unit according to the present embodiment controls the movementof the multiple focus lenses so that the amount of blur indicated by thecontrol information is satisfied in each of the in-range case and theout-of-range case, as indicated in (1) and (2) below, for example. Inother words, the lens unit according to the present embodiment controlsthe movement of the multiple focus lenses according to a method ofcontrol that depends on the object distance, for example. Herein, thecontrols indicated in (1) and (2) below correspond to an example ofcontrols based on different movement profiles, for example.

(1) Case in which Position of Each of Multiple Focus Lenses is in-Range

The lens unit according to the present embodiment computes the amount ofmovement for each of the multiple focus lenses by using a relationalexpression of satisfactory optical performance expressing a relationshipbetween the amount of blur and the amount of movement, for example. Therelationship between the amount of blur and the amount of movement maybe said to be a “relationship between the amount of movement of each ofthe multiple focus lenses and the amount of movement of the imageplane”, or a “relationship between the amount of blur at an arbitrarypoint of interest in-range and the amount of movement of the image plane(or the amount of movement of each of the multiple focus lensesrealizing the amount of movement of the image plane)”, for example.

Herein, the relational expression of satisfactory optical performancemay be, for example, an expression prescribing position relationshipsamong the multiple focus lenses so that even if the focal length (focaldepth, image plane) is changed, the amount of blur at the changed focallength (spatial frequency or MTF) satisfies a preset value. Especiallyin the case of the zoom lens unit, a plurality of the relationalexpressions corresponding to the plurality of focal length can beapplied.

In addition, the lens unit according to the present embodiment may alsocompute the amount of movement of each of the multiple focus lenses byreferencing, for example, a table (or a database; this applies similarlyhereinafter) associating the amount of blur with the amount of movementof each focus lens obtained from the above relational expression ofsatisfactory optical performance. Herein, the table associating theamount of blur with the amount of movement is stored in a recordingmedium, such as a recording medium provided in the lens unit accordingto the present embodiment, or a recording medium external to the lensunit according to the present embodiment, for example.

(2) Case in which Position of Each of Multiple Focus Lenses isOut-of-Range

When the position of each of the multiple focus lenses is out-of-range,imaging with satisfactory optical performance is not required. In otherwords, when the position of each of the multiple focus lenses isout-of-range, it is sufficient to control only the amount of blur.

Thus, the lens unit according to the present embodiment computes theamount of movement of each of the multiple focus lenses so as to satisfythe amount of blur indicated by the control information, and also sothat the proportion of the amount of blur for each focus lens isdifferent from the case of (1) above, for example.

Taking the case of computing the amount of movement of the focus lens L1and the focus lens L2 illustrated in FIG. 1 as an example, the lens unitaccording to the present embodiment computes the amount of movement ofthe focus lens L1 and the focus lens L2 according to Expression 1 below,for example. Note that if there are three or more focus lenses, a numberof terms equal to the number of focus lenses is added to Expression 1below.

The term “Z” indicated in Expression 1 below is the amount of blur perunit time indicated by the control information (expressed in units of[mm], for example). Also, the term “d₁” indicated in Expression 1 belowrepresents the amount of movement of the focus lens L1 (expressed inunits of [mm], for example), while the term “d₂” indicated in Expression1 below represents the amount of movement of the focus lens L2(expressed in units of [mm], for example).

In addition, the term “PK₁” indicated in Expression 1 below representsthe focus point sensitivity of the focus lens L1, while the term “PK₂”indicated in Expression 1 below represents the focus point sensitivityof the focus lens L2.

Herein, the focus point sensitivity is the amount of movement of theimage plane in a direction orthogonal to the optical axis direction onthe image sensor when the focus lens is operated for the unit time, andis a known value. For example, if the image plane moves 3 [mm] in thepositive direction of a direction orthogonal to the optical axisdirection when a certain focus lens moves 1 [mm], a focus pointsensitivity PK=3 is computed. As another example, if the image planemoves 3 [mm] in the negative direction of a direction orthogonal to theoptical axis direction when a certain focus lens moves 1 [mm], a focuspoint sensitivity PK=−3 is computed. The lens unit according to thepresent embodiment acquires data indicating the focus point sensitivitycorresponding to each focus lens by reading out data from a recordingmedium or the like provided in the lens unit according to the presentembodiment, for example.

Z=d ₁ ·PK ₁ +d ₂ ·PK ₂  (Expression 1)

Herein, the focus point sensitivity of a focus lens does not changegreatly when the position of the focus lens is out-of-range, and thusthe effects of change in the focus point sensitivity may be ignored. Inthis case, the burden ratio of the amount of blur (proportion of theamount of blur) for each focus lens depends on the amount of movement d₁of the focus lens L1 and the amount of movement d₂ of the focus lens L2.

The lens unit according to the present embodiment determines the amountof movement d₁ of the focus lens L1 and the amount of movement d₂ of thefocus lens L2 so that Expression 1 above is satisfied, and also so thatthe proportion of the amount of blur of each focus lens is different.

More specifically, in the case in which the position of each focus lensis out-of-range, the lens unit according to the present embodimentcontrols the movement of the multiple focus lenses as indicated in (2-1)to (2-4) below, for example. For example, by controlling the movement ofthe multiple focus lenses as indicated in (2-1) to (2-4) below, the“amount of movement per unit time of each focus lens in the case inwhich the position of each focus lens is out-of-range” may be madedifferent from the “amount of movement per unit time of each focus lensin the case in which the position of each focus lens is in-range”.

(2-1) First Example

When the position of each focus lens is out-of-range, the lens unitaccording to the present embodiment performs control so as to stop themovement of at least one focus lens among the multiple focus lenses.

In the lens unit according to the present embodiment, as discussedearlier, the movement of each focus lens is controlled by having thecontrol circuit transmit a control signal to an actuator to control theoperation of that actuator, for example. The control circuit, bytransmitting a control signal including an instruction to stop operationto an actuator corresponding to at least one focus lens among themultiple focus lenses, for example, stops movement of at least one focuslens among the multiple focus lenses. Note that if the above controlsignal is transmitted to the actuator while the focus lens is moving(that is, if movement of the focus lens is controlled to be stopped), inactual practice, the focus lens may move during the period between thecontrol signal being transmitted and the focus lens actually stopping,because of movement due to inertia and the like.

As above, by controlling so as to stop the movement of at least onefocus lens among the multiple focus lenses, the proportion of the amountof blur of each focus lens may be made different from the case of (1)above. Thus, by controlling so as to stop the movement of at least onefocus lens among the multiple focus lenses, the amount of movement perunit time of each focus lens in the out-of-range case may be madedifferent from the amount of movement per unit time of each focus lensin the in-range case.

(2-2) Second Example

When the position of each focus lens is out-of-range, the lens unitaccording to the present embodiment controls the amount of movement ofeach of the multiple focus lenses on the basis of one or both of thetype of focus lens, and the type of actuator corresponding to each ofthe multiple focus lenses.

(A) Examples of Control Based on Type of Focus Lens

The type of focus lens may be categorized by mass, for example. To giveone example, the types of focus lenses may be “large focus lens” and“small focus lens”, for example. A “large focus lens” may be referred toas a “heavy lens”, while a “small focus lens” may be referred to as a“light lens” in some cases.

Herein, “large focus lens” and “small focus lens” are classified on thebasis of one or multiple properties from among the f-number, mass, andfocus point sensitivity, for example.

To give an example, a focus lens classified as a “large focus lens” maybe a focus lens classified on the basis of set threshold values like thefollowing, for example.

-   -   f-number: 4.0 or less    -   mass: 100 [g] or more

Also, a focus lens classified as a “small focus lens” may be a focuslens classified on the basis of set threshold values like the following,for example.

-   -   f-number: greater than 4.0    -   mass: approximately 10 [g]

Note that examples of focus lenses classified into “large focus lens”and “small focus lens” are not limited to the examples indicated above.

For example, if the lens unit according to the present embodiment isprovided with two focus lenses, the focus lens of greater mass or thefocus lens having a smaller f-number may be designated the “large focuslens”, while the other focus lens may be designated the “small focuslens”.

Additionally, the type of focus lens according to the present embodimentmay also be classified by the actuator that operates the focus lens (theactuator corresponding to the focus lens), for example. For example, afocus lens that operates by an ultrasonic motor (particularly aring-type travelling wave ultrasonic motor) or a direct current (DC)motor is classified as a “large focus lens”, while a focus lens thatoperates by a linear actuator (linear motor), a stepping motor, or apiezo element (piezoelectric element) is classified as a “small focuslens”. At this point, for a motor that operates a large focus lens, areduction drive may also be used to obtain a large torque. Also, a motorthat operates a large focus lens is set with a large rotational speed,particularly compared to a motor that operates a small focus lens.

In addition, the type of focus lens according to the present embodimentmay also be classified on the basis of the focus point sensitivity asdiscussed earlier, for example. The examples given below are examples ofclassifications based on the focus point sensitivity.

-   -   If the focus point sensitivity is greater than a preset        threshold value (or if the focus point sensitivity is equal to        or greater than a preset threshold value), the focus lens is        classified as a “small focus lens”.    -   If the focus point sensitivity is less than or equal to a preset        threshold value (or if the focus point sensitivity is less than        a preset threshold value), the focus lens is classified as a        “large focus lens”.    -   If the lens unit according to the present embodiment is provided        with two focus lenses, the focus lens having a smaller focus        point sensitivity is designated the “large focus lens”, while        the other focus lens is designated the “small focus lens”.

For example, if the type of focus lens is a “large focus lens”, the lensunit according to the present embodiment performs control so as to notmove that focus lens, or to stop the movement of that focus lens.Herein, in the control according to the second example, controlling soas to stop the movement of a focus lens corresponds to a controlcombining the control according to the second example with the controlaccording to the first example indicated in (2-1) above (this appliessimilarly hereinafter).

Note that even if the type of focus lens is a “large focus lens”, thefocus lens may still be moved if the focus point sensitivity of thatfocus lens is greater than the set threshold value (or if the focuspoint sensitivity is equal to or greater than the threshold value).Herein, the threshold value may be a preset, fixed value, or a variablevalue that may be modified on the basis of a user operation or the like.

The example given below is an example of control in the case of moving afocus lens when the type of the focus lens is a “large focus lens”.

-   -   If the multiple focus lenses include a combination of a focus        lens corresponding to a “large focus lens” and a focus lens        corresponding to a “small focus lens”, the lens unit according        to the present embodiment controls the focus lens corresponding        to the “large focus lens” to have a smaller amount of movement        than when the type of focus lens is a “small focus lens”.

By controlling as above when the type of focus lens is a “large focuslens”, the power consumption related to focus lens movement may bedecreased further.

As another example, the examples given below are examples of controlwhen the type of the focus lens is a “small focus lens”.

If the type of focus lens is a “small focus lens”, the lens unitaccording to the present embodiment moves that focus lens.

-   -   If the multiple focus lenses include a combination of a focus        lens corresponding to a “large focus lens” and a focus lens        corresponding to a “small focus lens”, the lens unit according        to the present embodiment controls the focus lens corresponding        to the “small focus lens” to have a greater amount of movement        than when the type of focus lens is a “large focus lens”.

The examples given above are examples of control based on the type offocus lens. However, control based on the type of focus lens is notlimited to the examples indicated above. The lens unit according to thepresent embodiment may also specify the type of focus lens on the basisof arbitrary information enabling the specification of a focus lens (forexample, data indicating a serial number of a focus lens), and conductcontrol corresponding to the type of the specified focus lens.

(B) Examples of Control Based on Type of Actuator

Types of actuators may include, for example, types classified by thefocus lens that the actuator is capable of moving, and types classifiedby power consumption.

For example, the examples given below are examples of types classifiedby the focus lens that the actuator is capable of moving.

-   -   Actuator capable of moving a “large focus lens”, such as an        ultrasonic motor or a DC motor, for example    -   Actuator capable of moving a “small focus lens”, such as a        linear actuator, a stepping motor, or a piezo element        (piezoelectric element), for example

At this point, for example, if an ultrasonic motor or a DC motor is usedas an actuator, the focus lens cannot be driven directly by theactuator, and thus the positioning of the focus lens is performed byproviding a reduction mechanism between the actuator and the focus lens.As another example, if a linear actuator, a stepping motor, or a piezoelement (piezoelectric element) is used as an actuator, the focus lensmay be driven directly by the actuator, and thus the above reductionmechanism is not provided.

If the type of actuator is an actuator capable of moving a “large focuslens”, the lens unit according to the present embodiment performscontrol so as to not move the focus lens corresponding to that actuator,or to stop the movement of the focus lens corresponding to thatactuator, for example. Also, if the multiple focus lenses include acombination of a focus lens corresponding to a “large focus lens” and afocus lens corresponding to a “small focus lens”, the lens unitaccording to the present embodiment may also control the focus lenscorresponding to the “large focus lens” so that the amount of movementof the focus lens corresponding to the actuator is less than the case ofan actuator capable of moving a “small focus lens”, for example.

Also, if the type of actuator is an actuator capable of moving a “smallfocus lens”, the lens unit according to the present embodiment controlsmoves the focus lens corresponding to that actuator. Also, if themultiple focus lenses include a combination of a focus lenscorresponding to a “large focus lens” and a focus lens corresponding toa “small focus lens”, the lens unit according to the present embodimentcontrols the focus lens corresponding to the “small focus lens” so thatthe amount of movement of the focus lens corresponding to the actuatoris greater than the case of an actuator capable of moving the “largefocus lens”.

In addition, the examples given below are examples of types classifiedby power consumption. Types classified by power consumption areclassified on the basis of a result of a comparison between the powerconsumption and a set power consumption threshold value.

-   -   Actuator whose power consumption is equal to or greater than the        set power consumption threshold value (or actuator whose power        consumption is greater than the set power consumption threshold        value; this applies similarly hereinafter), such as an        ultrasonic motor or a DC motor, for example    -   Actuator whose power consumption is less than the set power        consumption threshold value (or actuator whose power consumption        is less than or equal to the set power consumption threshold        value; this applies similarly hereinafter), such as a linear        actuator, a stepping motor, or a piezo element (piezoelectric        element), for example

If the type of actuator is an actuator whose power consumption is equalto or greater than the set power consumption threshold value, the lensunit according to the present embodiment performs control so as to notmove the focus lens corresponding to that actuator, or to stop themovement of the focus lens corresponding to that actuator, for example.In addition, the lens unit according to the present embodiment may alsoperform control so that the amount of movement of the focus lenscorresponding to the actuator is less than the case of an actuator whosepower consumption is less than the set power consumption thresholdvalue, for example.

In addition, if the type of actuator is an actuator whose powerconsumption is less than the set power consumption threshold value, thelens unit according to the present embodiment performs control so thatthe amount of movement of the focus lens corresponding to the actuatoris greater than the case of an actuator whose power consumption is equalto or greater than the set power consumption threshold value, forexample.

The examples given above are examples of control based on the type ofactuator. However, control based on the type of actuator is not limitedto the examples indicated above. The lens unit according to the presentembodiment may also conduct control corresponding to a focus controlmethod supported by the actuator, a servo mechanism method supported bythe actuator (desired method), or the like.

(C) Example of Control Based on Type of Focus Lens and Type of Actuator

The lens unit according to the present embodiment may also control theamount of movement of each of the multiple focus lenses on the basis thetype of focus lens and the type of actuator.

To give an example, if the type of focus lens is a “large focus lens”and the type of actuator is an actuator capable of moving a “large focuslens”, the lens unit according to the present embodiment performscontrol so as to not move that focus lens, or to stop the movement ofthat focus lens. In addition, if the type of focus lens is a “smallfocus lens” and the type of actuator is an actuator capable of moving a“large focus lens”, the lens unit according to the present embodimentperforms control so that the amount of movement of the focus lens isgreater than the case of other combinations of a type of focus lens anda type of actuator.

(2-3) Third Example

When the position of each focus lens is out-of-range, the lens unitaccording to the present embodiment controls the amount of movement ofeach of the multiple focus lenses on the basis of the inter-groupdistance among the multiple focus lenses.

Herein, the inter-group distance according to the present embodiment isthe interval between focus lenses. The inter-group distance of focuslenses used in contrast AF is determined by the following factors, forexample.

-   -   Optical performance of the lens unit    -   Physical size (thickness) of the focus lenses    -   Mechanical members constituting actuators    -   Desirable range of motion for contrast AF    -   Amount of focus point correction (such as aperture) during        imaging    -   Flange back error in imaging unit (this corresponds to the body        of the imaging device, for example) corresponding to lens unit        (for the case in which the imaging device is an imaging device        with an interchangeable lens, for example)

The lens unit according to the present embodiment performs controlcorresponding to the inter-group distance by referencing, for example, atable (or a database) associating the inter-group distance with theamount of movement of each focus lens, for example.

In the lens unit according to the present embodiment, satisfactoryoptical performance is not required when out-of-range. Thus, the controlcorresponding to the inter-group distance may be, for example, controlthat does not provide satisfactory optical performance out-of-range andalso does not produce interference due to the inter-group distance(which is set without considering satisfactory optical performance), oralternatively, control that does not provide satisfactory opticalperformance out-of-range and also moves the multiple focus lenses nearthe limit of the inter-group distance (which is set without consideringsatisfactory optical performance). When control corresponding to theinter-group distance is performed, the inter-group distance is set so asnot to produce satisfactory optical performance out-of-range.

(2-4) Fourth Example

When the position of each focus lens is out-of-range, the lens unitaccording to the present embodiment controls the amount of movement ofeach of the multiple focus lenses on the basis of a priority set foreach of the multiple focus lenses. The priority is set on the basis ofan index related to the focus lens, such as the focus point sensitivityor the mass, for example. In addition, the priority may be a preset,fixed value, or a variable value that may be modified on the basis of auser operation or the like.

As an example of control based on priority, the amount of movement ispreferentially controlled for the focus lens with the highest priority,and the amount of movement for an other focus lens is controlled incorrespondence with the control of the preferentially controlled focuslens. Herein, the control for the focus lens with the highest prioritymay be controlling so as to move that focus lens, not moving that focuslens, or stop the movement of that focus lens. In the example of controlbased on priority indicated above, the focus lens with the highestpriority corresponds to a “primary focus lens”, while the other focuslens corresponds to a “secondary focus lens”, for example.

FIGS. 3 and 4 are explanatory diagrams for illustrating a control methodaccording to the present embodiment, and illustrate an example ofcontrolling focus lens position, whish is realized by conducting themovement control process according to the present embodiment. FIGS. 3and 4 illustrate an example of controlling the positions of the focuslens L1 and the focus lens L2 in the lens unit illustrated in FIG. 1.

The label A in FIG. 3 and the label A in FIG. 4 indicate an example ofthe positional relationship of the focus lens L1 and the focus lens L2,which is realized in accordance with the relationship of satisfactoryoptical performance between the amount of blur and the amount ofmovement discussed earlier. Also, the label B in FIG. 3 and the label Bin FIG. 4 illustrate an example of the positional relationship of thefocus lens L1 and the focus lens L2 at an out-of-range positionexceeding the position corresponding to the object distance 1 (theposition corresponding to infinity). Also, the label C in FIG. 3 and thelabel C in FIG. 4 illustrate an example of the positional relationshipof the focus lens L1 and the focus lens L2 at an out-of-range positionexceeding the position corresponding to the object distance 2 (theposition corresponding to the minimum object distance).

(a) First Example of Control of Focus Lens Position (FIG. 3)

If the focus point sensitivity of the focus lens L1 and the focus pointsensitivity of the focus lens L2 have the same sign, the lens unitaccording to the present embodiment controls the positions of the focuslens L1 and the focus lens L2 out-of-range as indicated by the labels Band C in FIG. 3, for example.

As discussed earlier, when out-of-range, the lens unit according to thepresent embodiment determines the amount of movement d1 of the focuslens L1 and the amount of movement d2 of the focus lens L2 so thatExpression 1 above is satisfied, and also so that the proportion of theamount of blur of each focus lens is different.

Thus, the amount of blur when the control of satisfactory opticalperformance labeled A in FIG. 3 is conducted out-of-range is the same asthe amount of blur when the controls labeled B and C in FIG. 3 areconducted out-of-range. In other words, when out-of-range past theposition corresponding to the object distance 1 (the positioncorresponding to infinity), the amount of blur indicated by the solidline (A in FIG. 3) and the amount of blur indicated by the dashed line(B in FIG. 3) are the same. Also, when out-of-range past the positioncorresponding to the object distance 2 (the position corresponding tothe minimum object distance), the amount of blur indicated by the solidline (A in FIG. 3) and the amount of blur indicated by the dashed line(C in FIG. 3) are the same.

(b) Second Example of Control of Focus Lens Position (FIG. 4)

If the focus point sensitivity of the focus lens L1 and the focus pointsensitivity of the focus lens L2 have different signs, the lens unitaccording to the present embodiment controls the positions of the focuslens L1 and the focus lens L2 out-of-range as indicated by the labels Band C in FIG. 4, for example.

As discussed earlier, when out-of-range, the lens unit according to thepresent embodiment determines the amount of movement d1 of the focuslens L1 and the amount of movement d2 of the focus lens L2 so thatExpression 1 above is satisfied, and also so that the proportion of theamount of blur of each focus lens is different. At this point, if thefocus point sensitivity of the focus lens L1 and the focus pointsensitivity of the focus lens L2 have different signs, to ensure theamount of blur in the same direction, the lens unit according to thepresent embodiment determines the amount of movement d1 of the focuslens L1 and the amount of movement d2 so that the actuator correspondingto the focus lens L1 and the actuator corresponding to the focus lens L2are driven in opposite directions. In other words, when the position ofeach of the multiple focus lenses changes from in-range to out-of-range,the lens unit according to the present embodiment may perform control tochange the movement direction of at least one focus lens.

Thus, in the second example of control of focus lens position, similarlyto the first example of control of focus lens position illustrated inFIG. 3, the amount of blur when the control of satisfactory opticalperformance labeled A in FIG. 4 is conducted out-of-range is the same asthe amount of blur when the controls labeled B and C in FIG. 4 areconducted out-of-range. In other words, when out-of-range past theposition corresponding to the object distance 1 (the positioncorresponding to infinity), the amount of blur indicated by the solidline (A in FIG. 4) and the amount of blur indicated by the dashed line(B in FIG. 4) are the same. Also, when out-of-range past the positioncorresponding to the object distance 2 (the position corresponding tothe minimum object distance), the amount of blur indicated by the solidline (A in FIG. 4) and the amount of blur indicated by the dashed line(C in FIG. 4) are the same.

The lens unit according to the present embodiment controls the positionsof the focus lens L1 and the focus lens L2 as illustrated in FIG. 3 or 4for the in-range case and the out-of-range case, for example.

FIG. 5 is an explanatory diagram for illustrating a control methodaccording to the present embodiment, and summarizes in one drawing thecontrols of the positions of the focus lens L1 and the focus lens L2illustrated in FIGS. 3 and 4.

As discussed above, while out-of-range, the amount of blur when controlof satisfactory optical performance is conducted (for example, the caseof A in FIG. 3 or A in FIG. 4) is the same as the amount of blur whenthe control according to the movement control process is conducted (forexample, the case of B in FIG. 3, C in FIG. 3, B in FIG. 4, or C in FIG.4). Also, taking the focus lens L1 in particular, the ranges of motionof the focus lens L1 while out-of-range become the ranges labeled A andB in FIG. 5, which are shorter than the ranges of motion of the focuslens L1 when the control of satisfactory optical performance isconducted (for example, the case of A in FIG. 3 or A in FIG. 4).

Thus, the lens unit according to the present embodiment is able toshorten the range of motion of the focus lens L1 while out-of-range,while still being able to acquire contrast values for conductingcontrast AF. Additionally, in the lens unit according to the presentembodiment, similar advantageous effects are also obtained for otherfocus lenses provided in the lens unit according to the presentembodiment, such as the focus lens L2.

Consequently, by conducting the movement control process according to acontrol method in accordance with the present embodiment, the lens unitaccording to the present embodiment is able to resolve an insufficiencyof focus lens movement which may occur when conducting contrastautofocus, as labeled D in FIG. 2, for example.

Additionally, by the control method according to the present embodiment,the range of motion of each of the multiple focus lenses whileout-of-range may be shortened, thereby making it easier to miniaturizethe lens unit according to the present embodiment.

Furthermore, in the movement control process according to a controlmethod in accordance with the present embodiment, control ofsatisfactory optical performance is performed while in-range, therebypreventing degraded optical performance due to the control method inaccordance with the present embodiment.

Lens Unit and Imaging Device According to Present Embodiment

Next, a configuration of a lens unit according to the present embodimentthat is able to conduct a process according to a control method inaccordance with the present embodiment discussed above, and aconfiguration of an imaging device according to the present embodimentthat is equipped with the lens unit according to the present embodiment,will be described.

[1] Example of Configuration of Lens Unit According to PresentEmbodiment

FIG. 6 is a block diagram illustrating an example of a configuration ofa lens unit 100 according to the present embodiment. FIG. 6 additionallyillustrates an example of a configuration of an imaging device 200which, together with the lens unit 100, constitutes the system of adigital camera with an interchangeable lens. In the system of a digitalcamera with an interchangeable lens illustrated in FIG. 6, the lens unit100 functions as the interchangeable lens. Also, in the system of adigital camera with an interchangeable lens illustrated in FIG. 6, theimaging device 200 functions as the main camera unit (also called thebody). In addition, the imaging device 200 corresponds to an example ofthe imaging unit discussed earlier. Hereinafter, an example of aconfiguration of the lens unit 100 will be described, with reference tothe lens unit 100 illustrated in FIG. 6 and the imaging device 200illustrated in FIG. 6 as appropriate.

[1-1] Imaging Device 200

The imaging device 200 is equipped with a connection section 202, animaging section 204, a signal processing section 206, an imageprocessing section 208, a control section 210, a power control section212, an operating section 214, a display section 216, and a storagesection 218, for example.

The imaging device 200 may also be equipped with components such asread-only memory (ROM; not illustrated) and random access memory (RAM;not illustrated), for example. The above structural elements of imagingdevice 200 are interconnected by a bus that acts as a data transmissionline, for example. The imaging device 200 is driven with power suppliedfrom an internal power source, such as a battery provided in the imagingdevice 200, or with power supplied from a connected external powersource, for example.

The above ROM stores programs and control data, such as computationalparameters, used by the control section 210. The above RAM temporarilystores information such as programs executed by the control section 210and the like, for example.

On the connection section 202, a mount to which the lens unit 100 may beremovably attached is provided. Near the mount constituting theconnection section 202, a holding member that holds one or multipleelectrical contacts is provided in a partially protruding state on theinner circumference of the mount.

When a connection section 102 of the lens unit 100 discussed later isattached to the connection section 202 of the imaging device 200, amount constituting the connection section 202 provided with multipleelectrical contacts is electrically and physically connected to themount constituting the connection section 102. By electricallyconnecting the connection section 202 and the connection section 102,power supply from the imaging device 200 to the lens unit 100, as wellas communication between the imaging device 200 and the lens unit 100,become possible, for example.

The imaging section 204 is an image sensor using multiple photo sensorssuch as a complementary metal-oxide-semiconductor (CMOS) sensor or acharge-couple device (CCD) sensor, and outputs an image signalcorresponding to light received through the lens unit 100.

The signal processing section 206 performs processes such as demosaicingon the image signal acquired from the imaging section 204, and generatesdata expressing a RAW image.

The image processing section 208 processes the image signal acquiredfrom the signal processing section 206. For example, in the case ofrecording a RAW image in the storage section 218, the image processingsection 208 losslessly compresses the RAW image, and causes the storagesection 218 to record the losslessly compressed image data. In addition,the image processing section 208 may also losslessly compress a RAWimage after first performing a process such as gamma correction, forexample, and then cause the storage section 218 to record the losslesslycompressed image data.

The image processing section 208 also includes a filter 220 and adetection section 222, for example.

The filter 220 removes noise components from the image signal acquiredfrom the signal processing section 206. The filter 220 may be anyarbitrary filter capable of removing noise components, such as asmoothing filter.

The detection section 222 includes a detector circuit, for example, anddetects the signal with noise components removed by the filter 220. Withthe detection by the detector circuit, data indicating contrast (forexample, data indicating contrast AF detection values; this is anexample of a detection result of a signal obtained by imaging) isobtained, for example.

The control section 210 includes one or multiple processors made up of acomputational circuit such as a micro-processing unit (MPU), forexample, and controls the imaging device 200 overall.

The processor constituting the control section 210 fulfills the role ofa blur amount control circuit that controls the amount of blur, forexample, and controls the amount of blur during imaging. Also, theprocessor constituting the control section 210 functions as acommunication controller, and fulfills a role of controlling wiredcommunication or wireless communication with an external device such asthe lens unit 100.

The control section 210 includes a communication control section 224 anda processing section 226, for example.

The communication control section 224 fulfills the role of controllingwired communication or wireless communication with an external devicesuch as the lens unit 100.

The processing section 226 determines the amount of blur per unit time,on the basis of a detection result obtained from the detector circuitconstituting the detection section 222 (a detection result of a signalobtained by imaging through the lens unit 100), for example.Subsequently, the communication control section 224 causes controlinformation indicating an amount of blur determined by the processingsection 226 to be transmitted to the lens unit 100.

FIG. 7 is a flowchart illustrating an example of a process by theimaging device 200 according to the present embodiment, and illustratesan example of a process by the control section 210 provided in theimaging device 200.

The control section 210 determines a detection period (S100), anddetermines a detection speed (S102). The detection period is determinedby a subject brightness estimated from a signal obtained by imagingthrough the lens unit 100, or by a subject brightness estimated on thebasis of a detection value from a sensor such as a luminance sensor.

The control section 210 determines the amount of blur Z per unit time,on the basis of a detection result obtained from the detector circuitconstituting the detection section 222 (a detection result of a signalobtained by imaging through the lens unit 100), for example (S104). Thecontrol section 210 determines the amount of blur Z per unit time byreferencing a table (or database) associating the contrast AF detectionvalue with the amount of blur Z, or by computing according to anarbitrary algorithm capable of obtaining the amount of blur Z based onthe contrast AF detection value, for example.

Subsequently, the control section 210 causes control informationindicating the amount of blur Z determined in step S104 to betransmitted to the lens unit 100 (S106)

The control section 210 conducts the process illustrated in FIG. 7, forexample. Obviously, however, the example of the process by the controlsection 210 is not limited to the example illustrated in FIG. 7.

Referring again to FIG. 6, an example of a configuration of the imagingdevice 200 will be described. The power control section 212 includes aprocessor or the like, and performs control related to the powersupplied from an internal power source (not illustrated) such as abattery provided in the imaging device 200, or from an external powersource. The power control section 212 performs power-related control onthe basis of the operational status of the imaging device 200, such asthe state of processing in the control section 210, for example. To givean example, the power control section 212 computes an amount of powerthat may be supplied to the lens unit 100 on the basis of theoperational status of the imaging device 200, and supplies power to thelens unit 100 through the connection section 202.

The operating section 214 is an operating section provided in theimaging device 200, and includes operating devices such as buttons, atouch panel, and a rotary operating member. A user using the imagingdevice 200 operates the operating section 214 to perform actions such assetting the imaging mode and setting imaging parameters, for example.

The display section 216 is a display section provided in the imagingdevice 200, and causes a display screen to display screens, such as ascreen presenting various images (moving images or still images) such asa live view image or a preview image, and a screen presenting a UI. Thedisplay section 216 includes a display device such as a liquid crystaldisplay (LCD) or an organic electro-luminescence display (organic ELdisplay), for example.

The storage section 218 is a storage section provided in the imagingdevice 200, and stores various data such as image data. The storagesection 218 may be non-volatile memory, for example. The storage section218 may also be removable from the imaging device 200.

With the configuration illustrated in FIG. 6, for example, the imagingdevice 200 transmits control information indicating the amount of blurper unit time to the lens unit 100. Obviously, however, theconfiguration of the imaging device 200 is not limited to theconfiguration illustrated in FIG. 6.

[1-2] Lens Unit 100

The lens unit 100 is equipped with a connection section 102, focuslenses 104A and 104B, driving sections 106A and 106B, position detectionsections 108A and 108B, and a control section 110, for example. The lensunit 100 is driven with power supplied from an internal power source,such as a battery provided in the lens unit 100, or with power suppliedfrom a connected external power source (for example, power supplied fromthe imaging device 200), for example.

On the connection section 102, a mount to which the imaging device 200may be removably attached is provided. Near the mount constituting theconnection section 102, a holding member that holds one or multipleelectrical contacts is provided in a partially protruding state on theinner circumference of the mount.

As discussed above, when the connection section 102 of the lens unit 100is attached to the connection section 202 of the imaging device 200, themount constituting the connection section 202 provided with multipleelectrical contacts is electrically and physically connected to themount constituting the connection section 102. By electricallyconnecting the connection section 202 and the connection section 102,power supply from the imaging device 200 to the lens unit 100, as wellas communication between the imaging device 200 and the lens unit 100,become possible, for example.

The focus lens 104A is a first focus lens provided in the lens unit 100.The focus lens 104A is made up of one focus lens or multiple focuslenses. Also, in FIG. 6, the focus lens 104A is the focus lens providedcloser to the subject than the other focus lens 104B.

The focus lens 104B is the other focus lens provided in the lens unit100. The focus lens 104B is made up of one focus lens or multiple focuslenses. The focus lens 104B may include the same type of focus lens asthe focus lens 104A, or a different type of focus lens.

The focus lenses 104A and 104B are provided in a lens barrel (notillustrated). Note that, as indicated with reference to FIG. 1, otherlenses such as a zoom lens may also be provided in the lens barrel.

The driving section 106A includes an actuator such as a linear actuator,a stepping motor, a piezo element (piezoelectric element), an ultrasonicmotor, or a DC motor, for example. The actuator constituting the drivingsection 106A is the actuator corresponding to the focus lens 104A, anddrives the focus lens 104A inside the lens barrel according to a controlsignal transmitted from the control section 110.

The driving section 106B includes an actuator such as a linear actuator,a stepping motor, a piezo element (piezoelectric element), an ultrasonicmotor, or a DC motor, for example. The actuator constituting the drivingsection 106B is the actuator corresponding to the focus lens 104B, anddrives the focus lens 104B inside the lens barrel according to a controlsignal transmitted from the control section 110. The actuatorconstituting the driving section 106B may be the same type of actuatoras the actuator constituting the driving section 106A, or a differenttype of actuator.

The position detection section 108A detects the position inside the lensbarrel of the focus lens 104A, while the position detection section 108Bdetects the position inside the lens barrel of the focus lens 104B. Theposition detection sections 108A and 108B include an arbitrary positiondetection sensor capable of detecting the position of a focus lens, suchas a position detection sensor made up of a magnet and a magneticdetection sensor, for example.

The control section 110 includes one or multiple processors made up of acomputational circuit such as an MPU, for example, and controls the lensunit 100 overall.

The processor constituting the control section 110 fulfills a role of acontrol circuit that is primarily responsible for conducting themovement control process according to the control method in accordancewith the present embodiment, and controls the movement of the multiplefocus lenses 104A and 104B. The processor constituting the controlsection 110 functions as a communication controller, and fulfills a roleof controlling wired communication or wireless communication with anexternal device such as the imaging device 200.

The control section 110 includes a communication control section 112 anda driving control section 114, for example.

The communication control section 112 fulfills the role of controllingwired communication or wireless communication with an external devicesuch as the imaging device 200.

The driving control section 114 controls the movement of the focuslenses 104A and 104B inside the lens barrel by controlling the operationof the actuator constituting each of the driving sections 106A and 106B.The driving control section 114 determines the position of the focuslenses 104A and 104B inside the lens barrel on the basis ofposition-indicating information transmitted from each of the positiondetection sections 108A and 108B.

To give an example, when the actuator constituting each of the drivingsections 106A and 106B is an actuator that supports control by driving afocus lens with small amplitudes (called “wobbling”; hereinafter, suchcontrol is designated “wobbling control”), the driving control section114 may also conduct wobbling control. The driving control section 114conducts wobbling control when a moving image is captured through thelens unit 100, for example. By conducting wobbling control in thedriving control section 114, for example, the lens unit 100 and theimaging device 200 become able to work in conjunction to detect thepositions of the focus lenses 104A and 104B at which the contrast valuereaches a maximum, on the basis of the magnitudes of contrast valuesobtained by imaging.

In addition, in the case of conducting wobbling control, the drivingcontrol section 114 switches the focus lens to operate by wobblingcontrol according cases like those indicated in (i) to (iii) below, forexample.

(i) Case in which Low Power is Demanded

The driving control section 114 decreases power consumption byconducting wobbling control on only one focus lens.

For example, if one of the focus lenses 104A and 104B is a “large focuslens” while the other is a “small focus lens”, the driving controlsection 114 conducts wobbling control on the focus lens corresponding tothe “small focus lens”. Actuators that support wobbling control include,for example, a stepping motor, a linear actuator, and a piezo element.

(ii) Case in which Large Blur is Produced During Imaging

The driving control section 114 conducts wobbling control on two focuslenses. In addition, by controlling the amount of blur Z on the basis ofExpression 1 above, for example, the driving control section 114decreases the amplitude of the focus lenses to reduce tactility andnoise.

(iii) Case in which Reduced Tactility and Noise is Demanded

The driving control section 114 conducts wobbling control on two focuslenses. In addition, by controlling the amount of blur Z on the basis ofExpression 1 above, for example, the driving control section 114 invertsthe driving phase by 180 [degrees] to cancel out the force produced andreduce tactility and noise.

In addition, the driving control section 114 causes informationindicating the lens position to be transmitted to an external device,such as the imaging device 200 electrically connected through theconnection section 102. At this point, the information indicating thelens position for the case in which the lens unit according to thepresent embodiment includes one focus lens may be data indicating theposition of that focus lens detected by a position detection section,for example. Also, examples of information indicating the lens positionfor the case in which the lens unit according to the present embodimentincludes multiple focus lenses include, for example, data indicating theposition of each of the multiple focus lenses, or data indicating avirtual position when treating the multiple focus lenses as a singlefocus lens.

In addition, the driving control section 114 fulfills a role of acontrol circuit that is primarily responsible for conducting themovement control process according to the control method in accordancewith the present embodiment, and controls the movement of the multiplefocus lenses 104A and 104B on the basis of control information.

The driving control section 114 conducts the movement control process onthe basis of control information acquired from the imaging device 200 bycommunication with the imaging device 200 controlled by thecommunication control section 112, for example.

FIG. 8 is a flowchart illustrating an example of a process by the lensunit 100 according to the present embodiment, and illustrates an exampleof a process by the control section 110 provided in the lens unit 100.

The control section 110 determines whether or not control informationwas received (S200). If control information was transmitted from theconnection section 102, the control section 110 determines that controlinformation was received.

In the case of determining that control information was received in stepS200, the control section 110 does not advance the process untildetermining that control information was received.

Also, in the case of determining that control information was receivedin step S200, the control section 110 determines whether or not thepositions of the focus lenses 104A and 104B are in-range (S202). Thecontrol section 110 determines whether or not the positions are in-rangeon the basis of position-indicating information transmitted from each ofthe position detection sections 108A and 108B.

In the case of determining that the positions are in-range in step S202,the control section 110 references a first movement profilecorresponding to the in-range case (S204). The first movement profilemay be, for example, data indicating a relational expression betweenfocus lenses (this corresponds to the relational expression ofsatisfactory optical performance expressing a relationship between theamount of blur and the amount of movement discussed earlier), or arelational table for the in-range case (this corresponds to the tableassociating the amount of blur with the amount of movement of each focuslens obtained from the above relational expression of satisfactoryoptical performance discussed earlier).

Also, in the case of not determining that the positions are in-range instep S202, the control section 110 references a second movement profilecorresponding to the out-of-range case (S206). The second movementprofile may be, for example, a relational table for the out-of-rangecase (for example, a table associating the amount of blur with theamount of movement of each focus lens in the out-of-range case). Notethat the above relational table for the in-range case and the aboverelational table for the out-of-range case may be a single table. If theabove relational table for the in-range case and the above relationaltable for the out-of-range case are a single table, the control section110 switches the movement profile to use for control by changing thereference location in the table according to the determination result instep S202.

Also, in the case of determining that control information was receivedin step S200, the control section 110 references the focus pointsensitivity of the focus lenses (S208). Note that although FIG. 8illustrates an example in which the processing of step S208 is conductedafter the processing of steps S202 to S206, the control section 110 mayalso conduct the processing of steps S202 to S206 after the processingof step S208, or conduct the processing of steps S202 to S206 and theprocessing of step S208 in parallel.

The control section 110 determines the amount of movement per unit timeof each of the multiple focus lenses, on the basis of the amount of blurindicated by the control information (S210). For example, when theposition of each focus lens is in-range, the control section 110determines the amount of movement per unit time of each of the multiplefocus lenses so that the relational expression of satisfactory opticalperformance is satisfied. As another example, when the position of eachfocus lens is out-of-range, the control section 110 determines theamount of movement per unit time of each of the multiple focus lenses soas to be controlled like in the first example indicated in (2-1) to thethird example indicated in (2-4).

The control section 110 transmits a control signal including a drivingcommand for driving the focus lenses by the amount of movementdetermined in step S210 to the actuators constituting the drivingsections 106A and 106B corresponding to the focus lenses (S212).

The control section 110 conducts the process illustrated in FIG. 8, forexample. Obviously, however, the example of the process by the controlsection 110 is not limited to the example illustrated in FIG. 8.

According to the configuration illustrated in FIG. 6, for example, thelens unit 100 conducts a process according to a control method inaccordance with the present embodiment. Consequently, with theconfiguration illustrated in FIG. 6, the lens unit 100 is able toexhibit the advantageous effects exhibited as a result of conducting aprocess according to a control method in accordance with the presentembodiment.

Note that the configuration of a lens unit 100 able to conduct aprocessing according to a control method in accordance with the presentembodiment is not limited to the configuration illustrated in FIG. 6.

For example, a lens unit able to conduct a process according to acontrol method in accordance with the present embodiment additionallymay be equipped with components such as an operating section (notillustrated) or a power control section (not illustrated).

The operating section (not illustrated) constituting a lens unitincludes operating devices such as buttons, a touch panel, and aring-shaped operating member, for example. A user using the lens unitoperates the operating section (not illustrated) to perform actions suchas setting the zoom position of the lens and setting an aperture value,for example.

The power control section (not illustrated) constituting a lens unitincludes a processor or the like, and fulfills a role of distributing anoptimal amount of power to each structural element of the lens unit, onthe basis of power supplied from an external device such as the imagingdevice 200, for example.

In addition, a lens unit able to conduct a process according to acontrol method in accordance with the present embodiment additionallymay be equipped with components such as a mechanism related to shakecorrection and a mechanism related to aperture correction, for example.

[2] Example of Configuration of Imaging Device According to PresentEmbodiment

Next, an example of a configuration of an imaging device according topresent embodiment will be illustrated. FIG. 9 is a block diagramillustrating an example of a configuration of an imaging device 300according to the present embodiment.

The imaging device 300 is equipped with a lens unit 302 and an imagingunit 304, for example.

The lens unit 302 has a configuration basically similar to the lens unit100 illustrated in FIG. 6. Specifically, the lens unit 302 differs fromthe lens unit 100 illustrated in FIG. 6 in that the lens unit 302 is notprovided with a communication controller for communicating with anexternal device such as a separate imaging device 200.

In the lens unit 302, a movement control process based on acquiredcontrol information is conducted by the driving control section 114,similarly to the lens unit 100 illustrated in FIG. 6. Herein, thecontrol information is transmitted from the imaging unit 304(specifically, the control section 210).

The imaging unit 304 has a configuration basically similar to theimaging device 200 illustrated in FIG. 6. Specifically, the imaging unit304 differs from the imaging device 200 illustrated in FIG. 6 in thatthe imaging unit 304 is not provided with a communication controller forcommunicating with an external device such as a separate lens unit 100.

In the imaging unit 304, the amount of blur during imaging is controlledby the control section 210, similarly to the imaging device 200illustrated in FIG. 6. In addition, the control section 210 constitutingthe imaging unit 304 transmits control information indicating thedetermined amount of blur to the driving control section 114 of the lensunit 302, which is connected by a wired connection, for example.

With the imaging device 300 illustrated in FIG. 9, in the lens unit 302,a process according to a control method in accordance with the presentembodiment is conducted on the basis of control information acquiredfrom the imaging unit 304. Consequently, with the configurationillustrated in FIG. 9, the imaging device 300 is able to exhibit theadvantageous effects exhibited as a result of conducting a processaccording to a control method in accordance with the present embodiment.

However, the configuration of an imaging device according to the presentembodiment is not limited to the example illustrated in FIG. 9. Forexample, the lens unit constituting the imaging device according to thepresent embodiment may also take a configuration similar to themodification of the lens unit 100 illustrated in FIG. 6.

Although the foregoing describes an imaging device as an example of thepresent embodiment, the present embodiment is not limited to such anexample. The present embodiment is applicable to various equipmentcapable of being equipped with imaging functions, such as a digitalstill camera, a digital video camera, a computer such as a personalcomputer (PC) or a server, an arbitrary wearable device used by beingworn on the user's body, such as an eyewear-style device, a watch-styledevice, or a wristband-style device, a communication device such as asmartphone, a tablet device, a game console, or a moving body such as anautomobile. Additionally, the present embodiment may also be applied toa processing integrated circuit (IC) embeddable in equipment like theabove, for example.

Program According to Present Embodiment

By having a processor or the like in a computer execute a programenabling the execution of a process according to a control method inaccordance with the present embodiment (for example, the movementcontrol process discussed above), an insufficiency of focus lensmovement that may occur when conducting contrast autofocus may beresolved.

Additionally, by having a processor or the like in a computer execute aprogram enabling the execution of a process according to a controlmethod in accordance with the present embodiment, the advantageouseffects exhibited by a process according to a control method inaccordance with the present embodiment discussed above may be exhibited.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

For example, although the above indicates that a program enabling theexecution of a process according to a control method in accordance withthe present embodiment is provided, in the present embodiment, the aboveprogram may also be provided in conjunction with a recording medium onwhich the above program is stored.

The foregoing configuration illustrates one example of the presentembodiment, and obviously belongs to the technical scope of the presentdisclosure.

In addition, the effects described in the present specification aremerely illustrative and demonstrative, and not limitative. In otherwords, the technology according to the present disclosure can exhibitother effects that are evident to those skilled in the art along with orinstead of the effects based on the present specification.

Additionally, the present technology may also be configured as below.

-   (1) A lens unit including:    -   a plurality of focus lenses;    -   a plurality of actuators respectively corresponding to the        plurality of focus lenses and configured to move each of the        plurality of focus lenses; and    -   control circuitry configured to control movement of the        plurality of focus lenses according to a rule in a case of a        position of at least one of the plurality of focus lenses being        outside a designated range of satisfactory optical performance,        the rule being different from a rule in a case of the position        all of the plurality of focus lenses being inside the range. (2)        The lens unit according to (1), wherein    -   at least one of the plurality of focus lenses is a lens group        made up of a plurality of sub-lenses.-   (3) The lens unit according to (1) or (2), wherein    -   the control circuitry controls the movement of the plurality of        focus lenses based on control information indicating an amount        of blur per unit time.-   (4) The lens unit according to (3), wherein    -   the control circuitry controls the movement of the plurality of        focus lenses so that the amount of blur indicated by the control        information is satisfied in the case of the position of each of        the focus lenses being inside the range, and also satisfied in        the case of being outside the range.-   (5) The lens unit according to any one of (1) to (4), wherein    -   the control circuitry performs control so that an amount of        movement per unit time of each of the plurality of focus lenses        is different between the case of the position of each of the        plurality of focus lenses being inside the range, and the case        of being outside the range.-   (6) The lens unit according to (5), wherein    -   the control circuitry performs control to stop the movement of        at least one focus lens among the plurality of focus lenses in        the case of the position of each of the focus lenses being        outside the range.-   (7) The lens unit according to (5) or (6), wherein    -   in the case of the position of each of the focus lenses being        outside the range, the control circuitry controls the amount of        movement of each of the plurality of focus lenses based on a        type of the focus lens.-   (8) The lens unit according to any one of (5) to (7), wherein    -   in the case of the position of each of the focus lenses being        outside the range, the control circuitry controls the amount of        movement of each of the plurality of focus lenses based on a        type of the actuator corresponding to each of the plurality of        focus lenses.-   (9) The lens unit according to (5), wherein    -   in the case of the position of each of the focus lenses being        outside the range, the control circuitry controls the amount of        movement of each of the plurality of focus lenses based on an        inter-group distance among the plurality of focus lenses.-   (10) The lens unit according to any one of (1) to (9), wherein    -   the control circuitry performs control to change a movement        direction of at least one of the focus lenses based on a change        of the position of each of the plurality of focus lenses from        being inside the range to being outside the range.-   (11) The lens unit according to any one of (1) to (10), wherein    -   in the case of the position of each of the plurality of focus        lenses being inside the range, an object distance based on the        plurality of focus lenses is positioned between a minimum object        distance and infinity.-   (12) An imaging device including:    -   a lens unit; and    -   an imaging unit, wherein    -   the lens unit includes        -   a plurality of focus lenses,        -   a plurality of actuators respectively corresponding to the            plurality of focus lenses and configured to move each of the            plurality of focus lenses, and        -   a control circuitry configured to control movement of the            plurality of focus lenses according to a rule in a case of a            position of at least one of the plurality of focus lenses            being outside a designated range of satisfactory optical            performance, the rule being different from a rule in a case            of the position all of the plurality of focus lenses being            inside the range. (13) The imaging device according to (12),            wherein    -   the imaging unit includes a blur amount control circuitry        configured to control an amount of blur, and    -   the control circuitry of the lens unit controls the movement of        the plurality of focus lenses based on control information        indicating an amount of blur per unit time acquired from the        imaging unit.-   (14) The imaging device according to (13), wherein    -   the blur amount control circuitry of the imaging unit        -   determines the amount of blur per unit time on the basis of            a detection result of a signal obtained by imaging through            the lens unit, and        -   causes control information indicating the determined amount            of blur to be transmitted to the lens unit.-   (15) A control method executed by a control circuit of a lens unit,    the control method including:    -   controlling movement of a plurality of focus lenses provided        inside a lens barrel according to different rules between a case        of a position of each of the plurality of focus lenses being        inside a designated range of satisfactory optical performance,        and a case of being outside the range.-   (16) A lens unit including:    -   a plurality of focus lenses;    -   a plurality of actuators respectively corresponding to the        plurality of focus lenses and configured to move each of the        plurality of focus lenses; and    -   a control circuitry configured to control movement of the        plurality of focus lenses according to a rule in a case of        satisfactory optical performance, the rule being different from        a rule in a case of unsatisfactory optical performance,    -   wherein a range of satisfactory optical performance is        determined based on a positions of all of the plurality of focus        lenses.-   (17) The lens unit according to (16), wherein    -   at least one of the plurality of focus lenses is a lens group        made up of a plurality of sub-lenses.-   (18) The lens unit according to (16) or (17), wherein    -   the control circuitry controls the movement of the plurality of        focus lenses based on control information indicating an amount        of blur per unit time.-   (19) The lens unit according to (18), wherein    -   the control circuitry controls the movement of the plurality of        focus lenses so that the amount of blur indicated by the control        information is satisfied in the case of the position of each of        the focus lenses being inside the range, and also satisfied in        the case of being outside the range.-   (20) The lens unit according to any one of (16) to (19), wherein    -   the control circuitry performs control so that an amount of        movement per unit time of each of the plurality of focus lenses        is different between the case of the position of each of the        plurality of focus lenses being inside the range, and the case        of being outside the range.-   (21) The lens unit according to (20), wherein    -   the control circuitry performs control to stop the movement of        at least one focus lens among the plurality of focus lenses in        the case of the position of each of the focus lenses being        outside the range.-   (22) The lens unit according to (20) or (21), wherein    -   in the case of the position of each of the focus lenses being        outside the range, the control circuitry controls the amount of        movement of each of the plurality of focus lenses based on a        type of the focus lens.-   (23) The lens unit according to any one of (20) to (22), wherein    -   in the case of the position of each of the focus lenses being        outside the range, the control circuitry controls the amount of        movement of each of the plurality of focus lenses based on a        type of the actuator corresponding to each of the plurality of        focus lenses.-   (24) The lens unit according to (20), wherein    -   in the case of the position of each of the focus lenses being        outside the range, the control circuitry controls the amount of        movement of each of the plurality of focus lenses based on an        inter-group distance among the plurality of focus lenses.-   (25) The lens unit according to any one of (16) to (24), wherein    -   the control circuitry performs control to change a movement        direction of at least one of the focus lenses based on a change        of the position of each of the plurality of focus lenses from        being inside the range to being outside the range.-   (26) The lens unit according to any one of (16) to (25), wherein    -   in the case of the position of each of the plurality of focus        lenses being inside the range, an object distance based on the        plurality of focus lenses is positioned between a minimum object        distance and infinity.-   (27) A lens unit including:    -   a plurality of focus lenses;    -   a plurality of actuators respectively corresponding to the        plurality of focus lenses and configured to move each of the        plurality of focus lenses; and    -   a control circuitry configured to control movement of the        plurality of focus lenses, so that the plurality of focus lenses        satisfy a designated optical performance in a case that an        object distance is inside of a designated range, and the        plurality of focus lenses does not satisfy the designated        optical performance in a case that the objective distance is        outside of the designated range.-   (28) The lens unit according to (27), wherein    -   at least one of the plurality of focus lenses is a lens group        made up of a plurality of sub-lenses.-   (29) The lens unit according to (27) or (28), wherein    -   the control circuitry controls the movement of the plurality of        focus lenses based on control information indicating an amount        of blur per unit time.-   (30) The lens unit according to (29), wherein    -   the control circuitry controls the movement of the plurality of        focus lenses so that the amount of blur indicated by the control        information is satisfied in the case of the position of each of        the focus lenses being inside a range, and also satisfied in the        case of being outside the range.-   (31) The lens unit according to any one of (27) to (30), wherein    -   the control circuitry performs control so that an amount of        movement per unit time of each of the plurality of focus lenses        is different between the case of the position of each of the        plurality of focus lenses being inside the range, and the case        of being outside the range.-   (30) The lens unit according to (31), wherein    -   the control circuitry performs control to stop the movement of        at least one focus lens among the plurality of focus lenses in        the case of the position of each of the focus lenses being        outside the range.-   (31) The lens unit according to (29) or (30), wherein    -   in the case of the position of each of the focus lenses being        outside the range, the control circuitry controls the amount of        movement of each of the plurality of focus lenses based on a        type of the focus lens.-   (32) The lens unit according to any one of (29) to (31), wherein    -   in the case of the position of each of the focus lenses being        outside the range, the control circuitry controls the amount of        movement of each of the plurality of focus lenses based on a        type of the actuator corresponding to each of the plurality of        focus lenses.-   (33) The lens unit according to (29), wherein    -   in the case of the position of each of the focus lenses being        outside the range, the control circuitry controls the amount of        movement of each of the plurality of focus lenses based on an        inter-group distance among the plurality of focus lenses.-   (34) The lens unit according to any one of (27) to (33), wherein    -   the control circuitry performs control to change a movement        direction of at least one of the focus lenses based on a change        of the position of each of the plurality of focus lenses from        being inside the range to being outside the range.-   (35) The lens unit according to any one of (27) to (34), wherein    -   in the case of the position of each of the plurality of focus        lenses being inside the range, an object distance based on the        plurality of focus lenses is positioned between a minimum object        distance and infinity.-   (36) The lens unit according to any one of (27) to (35), wherein    -   the designated range is between a minimum object distance and an        infinity.

1. A lens unit comprising: a plurality of focus lenses arranged insequence such that light passes through the plurality of focus lenses inthat sequence; a plurality of actuators respectively corresponding tothe plurality of focus lenses and configured to move each of theplurality of focus lenses; and control circuitry configured to controlthe plurality of actuators to control movement of the plurality of focuslenses according to a rule in a case of a position of at least one ofthe plurality of focus lenses being outside a designated range ofsatisfactory optical performance, the rule being different from a rulein a case of the position all of the plurality of focus lenses beinginside the designated range.
 2. The lens unit according to claim 1,wherein at least one of the plurality of focus lenses is a lens groupmade up of a plurality of sub-lenses.
 3. The lens unit according toclaim 1, wherein at least one of the plurality of focus lenses is madeup of a single lens.
 4. The lens unit according to claim 1, wherein thecontrol circuitry controls the movement of the plurality of focus lensesbased on control information indicating an amount of blur per unit time.5. The lens unit according to claim 4, wherein the control circuitrycontrols the movement of the plurality of focus lenses so that theamount of blur indicated by the control information is satisfied in thecase of the position of each of the plurality of focus lenses beinginside the range, and also satisfied in the case of being outside therange.
 6. The lens unit according to claim 1, wherein the controlcircuitry performs control so that an amount of movement per unit timeof each of the plurality of focus lenses is different between the caseof the position of each of the focus lenses being inside the range, andthe case of being outside the range.
 7. The lens unit according to claim6, wherein the control circuitry performs control to stop the movementof at least one focus lens among the plurality of focus lenses in thecase of the position of each of the focus lenses being outside therange.
 8. The lens unit according to claim 6, wherein in the case of theposition of each of the focus lenses being outside the range, thecontrol circuitry controls the amount of movement of each of theplurality of focus lenses based on a type of the focus lenses.
 9. Thelens unit according to claim 6, wherein in the case of the position ofeach of the focus lenses being outside the range, the control circuitrycontrols the amount of movement of each of the plurality of focus lensesbased on a type of the actuator corresponding to each of the pluralityof focus lenses.
 10. The lens unit according to claim 6, wherein in thecase of the position of each of the focus lenses being outside therange, the control circuitry controls the amount of movement of each ofthe plurality of focus lenses based on an inter-group distance among theplurality of focus lenses.
 11. (canceled)
 12. The lens unit according toclaim 1, wherein in the case of the position of each of the plurality offocus lenses being inside the range, an object distance based on theplurality of focus lenses is positioned between a minimum objectdistance and infinity.
 13. An imaging device comprising: a lens unit;and imaging circuitry, wherein the lens unit includes a plurality offocus lenses arranged in sequence such that light passes through theplurality of focus lenses in that sequence, a plurality of actuatorsrespectively corresponding to the plurality of focus lenses andconfigured to move each of the plurality of focus lenses, and controlcircuitry configured to control the plurality of actuators to controlmovement of the plurality of focus lenses according to a rule in a caseof a position of at least one of the plurality of focus lenses beingoutside a designated range of satisfactory optical performance, the rulebeing different from a rule in a case of the position all of theplurality of focus lenses being inside the designated range.
 14. Theimaging device according to claim 13, wherein the imaging circuitryincludes blur amount control circuitry configured to control an amountof blur, and the control circuitry of the lens unit is configured tocontrol the movement of the plurality of focus lenses based on controlinformation indicating an amount of blur per unit time acquired from theimaging circuitry.
 15. The imaging device according to claim 14, whereinthe blur amount control circuit determines the amount of blur per unittime on the basis of a detection result of a signal obtained by imagingthrough the lens unit, and causes control information indicating thedetermined amount of blur to be transmitted to the lens unit.
 16. Theimaging device according to claim 13, wherein at least one of theplurality of focus lenses is a lens group made up of a plurality ofsub-lenses.
 17. The imaging device according to claim 14, wherein thecontrol circuitry controls the movement of the plurality of focus lensesso that the amount of blur indicated by the control information issatisfied in the case of the position of each of the plurality of focuslenses being inside the range, and also satisfied in the case of beingoutside the range.
 18. The imaging device according to claim 13, whereinthe control circuitry performs control so that an amount of movement perunit time of each of the plurality of focus lenses is different betweenthe case of the position of each of the focus lenses being inside therange, and the case of being outside the range.
 19. The imaging deviceaccording to claim 18, wherein the control circuitry performs control tostop the movement of at least one focus lens among the plurality offocus lenses in the case of the position of each of the focus lensesbeing outside the range.
 20. The imaging device according to claim 17,wherein in the case of the position of each of the focus lenses beingoutside the range, the control circuitry controls the amount of movementof each of the plurality of focus lenses based on an inter-groupdistance among the plurality of focus lenses.
 21. The imaging deviceaccording to claim 13, wherein in the case of the position of each ofthe plurality of focus lenses being inside the range, an object distancebased on the plurality of focus lenses is positioned between a minimumobject distance and infinity.
 22. A control method comprising:controlling, via control circuitry and a plurality of actuators,movement of a plurality of focus lenses according to a rule in a case ofa position of at least one of the plurality of focus lenses beingoutside a designated range of satisfactory optical performance, the rulebeing different from a rule in a case of the position all of theplurality of focus lenses being inside the designated range, wherein theplurality of focus lenses are arranged in sequence such that lightpasses through the plurality of focus lenses in that sequence.
 23. Thecontrol method according to claim 22, wherein the control circuitrycontrols the movement of the plurality of focus lenses based on controlinformation indicating an amount of blur per unit time.
 24. The controlmethod according to claim 22, wherein at least one of the plurality offocus lenses is a lens group made up of a plurality of sub-lenses. 25.The control method according to claim 23, further comprising:controlling the movement of the plurality of focus lenses so that anamount of blur indicated by the control information is satisfied in thecase of the position of each of the plurality of focus lenses beinginside the range, and also satisfied in the case of being outside therange.
 26. The control method according to claim 22, further comprising:performing control so that an amount of movement per unit time of eachof the plurality of focus lenses is different between the case of theposition of each of the focus lenses being inside the range, and thecase of being outside the range.
 27. The control method according toclaim 26, further comprising: performing control to stop the movement ofat least one focus lens among the plurality of focus lenses in the caseof the position of each of the focus lenses being outside the range. 28.The control method according to claim 25, further comprising:controlling, in the case of the position of each of the focus lensesbeing outside the range, the amount of movement of each of the pluralityof focus lenses based on an inter-group distance among the plurality offocus lenses.
 29. The control method according to claim 22, wherein inthe case of the position of each of the plurality of focus lenses beinginside the range, an object distance based on the plurality of focuslenses is positioned between a minimum object distance and infinity. 30.The control method according to claim 22, wherein the control circuitryperforms control to change a movement direction of at least one of thefocus lenses based on a change of the position of each of the pluralityof focus lenses from being inside the range to being outside the range.31. A lens unit comprising: a plurality of focus lenses arranged insequence such that light passes through the plurality of focus lenses inthat sequence; a plurality of actuators respectively corresponding tothe plurality of focus lenses and configured to move each of theplurality of focus lenses; and control circuitry configured to controlthe plurality of actuators to control movement of the plurality of focuslenses according to a rule in a case of a position of at least one ofthe plurality of focus lenses being outside a designated range ofsatisfactory optical performance, the rule being different from a rulein a case of the position all of the plurality of focus lenses beinginside the designated range, wherein the control circuitry performscontrol of movement of at least one of the focus lenses based on achange of the position of each of the plurality of focus lenses frombeing inside the range to being outside the range